American bullfrog

Bullfrogs eat almost any small animal they can catch.

They eat insects, worms, crayfish and even other frogs. Bullfrog tadpoles mostly eat water plants.

Adult bullfrogs are predators with big appetites. They eat insects, worms, crayfish and other crustaceans, snakes, other frogs, tadpoles and the eggs of fish and salamanders, and they will even eat smaller bullfrogs.

A bullfrog hunts by sitting still and waiting. When something tasty comes close, its tongue flicks out in a flash and pulls the food into its wide mouth. Bullfrog tadpoles are different: they mostly graze on water plants.

Adults are generalist predators. Animal Diversity Web lists snakes, worms, insects, crustaceans, frogs, tadpoles and the aquatic eggs of fish, frogs, insects and salamanders, as well as cannibalism and a few reported cases of bats. Tadpoles mostly graze on aquatic plants.

Foraging is sit-and-wait: a bullfrog may wait a long time before a rapid tongue strike pulls prey into the mouth. Bullfrogs are active by day and night, most of all in warm, moist weather. Where they have been introduced, they are efficient predators of native frogs and tadpoles.

In spring and summer, boy bullfrogs call 'jug-o-rum'.

Their deep voices are very loud. In winter, bullfrogs rest in the mud until it is warm again.

In the breeding season, male bullfrogs call with a deep, rumbling 'jug-o-rum'. The call is so low and loud that it can be heard more than a kilometer away.

Male bullfrogs guard their own stretch of shoreline, from about 3 to 25 meters long, and wrestle other males that come too close. When winter comes, bullfrogs hibernate: most bury themselves in the mud under the water and rest until it is warm again.

The male's advertisement call is a low-frequency series of deep bass notes, usually written 'jug-o-rum', audible for more than a kilometer. Males are territorial, defending 3 to 25 meters of shoreline by wrestling intruders.

Bullfrogs prefer warm weather and hibernate in cold seasons, burying themselves in mud. Juveniles can disperse long distances over land, and adult home ranges have been estimated at about 1.6 kilometers.

In their home ponds, bullfrogs are doing well.

People took bullfrogs to many faraway places. There, they eat the local frogs. People should never let pet frogs go in the wild.

In its native home, the American bullfrog is common and listed as Least Concern. Bullfrogs help by eating lots of insects.

But people have carried bullfrogs to the western United States, South America, Europe and Asia, mostly to raise them for food, and some escaped. In places like California, these newcomers eat and outcompete native frogs and are helping push some of them toward extinction. That is why animals kept as pets or on farms should never be released into the wild.

The IUCN assessed the species (as Aquarana catesbeianus) as Least Concern in 2020, with an increasing population, native to Canada, the United States and Mexico and introduced in more than 25 other countries and territories; the IUCN's Global Invasive Species Database lists more still, including South Korea. Introductions began on the U.S. West Coast in the 1850s for food and spread globally through food farming and escapes from aquaculture; fish stocking may also have spread bullfrogs accidentally.

Introduced bullfrogs may be driving native frogs toward extinction in parts of California and Colorado. Their advantages include a higher tolerance of warm water than most frogs, a long breeding season, good survival of young and eggs and tadpoles that many fish find distasteful.